Alfentanil

CAS RN: 71195-58-9

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 680(SRC), determined from a structure estimation method(2), indicates that alfentanil is expected to have low mobility in soil(SRC). The pKa of alfentanil is 6.5(3), indicating that this compound will exist partially in cation form in the environment and cations generally adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(4). Volatilization of the cation from moist soil is not expected because cations do not volatilize(SRC). Volatilization of neutral alfentanil from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 9.7X10-20 atm-cu m/mole(SRC), using a fragment constant estimation method(5). Alfentanil is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 6.4X10-11 mm Hg at 25 deg C(SRC), determined from a fragment constant method(2). Biodegradation data in soil were not available(SRC, 2017).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 680(SRC), determined from a structure estimation method(2), indicates that alfentanil is expected to adsorb to suspended solids and sediment(SRC). An pKa of 6.5(3) indicates alfentanil will exist partially in the cation form at pH values of 5 to 9 and, therefore, volatilization of the cation from water surfaces is not expected to be an important fate process(SRC). Volatilization from water surfaces of neutral alfentanil is not expected(4) based upon an estimated Henry's Law constant of 9.7X10-20 atm-cu m/mole(SRC), developed using a fragment constant estimation method(5). Alfentanil is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(4). According to a classification scheme(6), an estimated BCF of 12(SRC), from its log Kow of 2.16(7) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is low. Biodegradation data in water were not available(SRC, 2017).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), alfentanil, which has an estimated vapor pressure of 6.4X10-11 mm Hg at 25 deg C(SRC), determined from a fragment constant method(2), is expected to exist solely in the particulate phase. Particulate-phase alfentanil may be removed from the air by wet and dry deposition(SRC). Alfentanil contains chromophores that absorb at wavelengths >290 nm(3) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).
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